Vehicle seat and method for controlling the same

ABSTRACT

Vehicle seat which effects a sideways movement of the occupant sitting on the vehicle seat during a lateral impact or directly before a lateral impact. The sideways movement takes place away from the side of the vehicle which faces the impact and toward the center of the vehicle, at least one seat cushion being transversely displaceable separately in relation to the seat components and in relation to the seat fixing elements for the sideways movement.

This application is a National Phase of international patent applicationno. PCT/EP02/09492, filed Aug. 24, 2002, the entire disclosure of whichis incorporated herein by reference. Priority is claimed based on Germanpatent application no. 101 50 719.4, filed Oct. 13, 2001.

BACKGROUND AND SUMMARY OF THE INVENTION

The invention relates to a vehicle seat which effects a relativemovement of the occupant sitting on it away from a side of the vehiclewhich faces a lateral impact toward a center of the vehicle during orimmediately debore the lateral impact and to a method for controllingthe vehicle seat.

DE 3023035 A1, which forms the generic type, discloses a vehicle seatwhich is suitable for considerably reducing the load on the occupantduring a lateral impact. The seat comprises a seat bracket which permitsa transverse movement of the seat relative to the seat mount in thevehicle during a lateral impact. The transverse movement can take placeby means of a transverse displacement drive, with the result that, if acollision object intrudes into the vehicle, the vehicle occupantundergoes a relative movement away from the intrusion site and towardthe center of the vehicle by the transverse movement of the entire seatin the direction of action of the impact. The transverse movement of theseat can be controlled in such a manner that the displacement of theseat is initiated before the forces arising from the intrusion have aneffect, the displacement forces and the moment of displacement beingadapted to give an optimum protective action.

It is the object of the invention to specify a vehicle seat and a methodfor controlling the vehicle seat, with which an occupant can beprotected to the greatest possible extent by virtue of his displacementduring a lateral impact. This object is achieved in respect of thevehicle seat wherein at least one seat cushion can be displacedseparately in relation to other seat components and seat fixing elementstransversely with respect to the longitudinal axis of the vehicle and isachieved in respect of the method by transverse displacement of the seatcushion begins before the moment of collision.

The invention is based on a vehicle seat in a motor vehicle whicheffects a relative movement of the occupant sitting on it away from theside of the vehicle which faces the impact toward the center of thevehicle during a lateral impact. As an alternative to this, the lateraldisplacement of the vehicle occupant may also already be initiatedbefore the moment of collision. According to the invention, in order todisplace an occupant, rather than the vehicle seat being displaceable asa whole, an individual seat component, in particular a seat cushion, isdisplaceable transversely with respect to the longitudinal axis of thevehicle independently of the rest of the vehicle seat. It isself-evident that also a plurality of seat cushions may be individuallylaterally displaceable. It is an advantage of the invention that themass which is to be accelerated is reduced, this making a smallerdisplacement unit possible which can be accelerated and braked morerapidly. The constructional space to be kept for the displacement isreduced, since other seat components, for example the seat frame, arenot displaced. A further advantage is that a larger displacementdistance for an occupant is made possible than is the case if the entireseat is displaced. An additional advantage of a vehicle seat accordingto the invention is that parts of the vehicle seat which are notdisplaced, for example a seat frame or a mechanism for displacing theseat longitudinally, can absorb additional deformation energy.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 a-1 c schematically illustrate a vehicle seat, seat cushion andoccupant displacement in accordance with an embodiment of the presentinvention. FIG. 1 a shows an initial seat and occupant position; FIG. 1b shows displacement of the seat cushion and the lower portion of theoccupant's body; FIG. 1 c shows displacement of the seat back and theupper portion of the occupant's body.

DETAILED DESCRIPTION

The displaceable seat cushions are parts of the vehicle seat which havea frictional or positive connection with the occupant, and so theirdisplacement enables a transverse displacement of the occupant to takeplace. In different configurations of the vehicle seat, seat cushions ofthis type may be, for example, a seat surface, a seat back, a headrestraint, a seat side cushion or an arm rest. A seat having thepossibility of an independent displacement of two or more seat cushionswhich can be displaced simultaneously or offset in time makes itpossible to further increase the protective action which can be achievedfor an occupant. As shown in FIGS. 1 a-1 c, the transverse displacementof an occupant 1, i.e. the displacement of the desired body parts/bodyregions of the occupant in the direction of the center of the vehicle(toward the right in the figures), takes place by means of a transfer offorce 2 to the occupant by the seat cushion 3 (FIG. 1 b) or the seatback 4 (FIG. 1 c).

In one development of the vehicle seat, a locking device is provided fora displaceable seat cushion 3, said locking device, following atransverse displacement which has taken place, securing the transverselydisplaced seat cushion in its end position. The locking device may be amechanical device which is automatically effective after the seatcushion has reached a predeterminable end position. As an alternative tothis, an activatable locking device which secures the seat cushion in anend position may be provided. In the case of the activatable lockingdevice, a plurality of different end positions can be predetermined by acontrol unit, it being possible for the end positions to bepredetermined as a function of occupant parameters and/or accidentparameters. The advantage of this development is that the vehicle seathas a defined position after the transverse displacement of a seatcushion, which means that further protective measures for the occupantcan be initiated in a specific manner. In one simple configuration, thelocking of a transversely displaced seat cushion at the end of thedisplacement distance can take place by a structurally predeterminableincrease in the friction at the end of a running rail.

If an advance determination of accident parameters, such as moment ofaccident and intrusion site, takes place with sufficient accuracy, thenthe transverse displacement of an occupant by means of a vehicle seataccording to the invention can be adapted in respect of the timesequence and in respect of the displacement distances, in particularwhen there is a plurality of seat cushions which can be displacedindependently of one another, to an accident, and, given appropriaterecognition of the occupant, also to an occupant.

A method for controlling the vehicle seat according to the invention isspecified below. In this method for the transverse displacement of aseat cushion of a vehicle seat according to the invention, thetransverse displacement of the seat cushion is initiated before themoment of collision, in particular the actual transverse displacementalready begins before the moment of collision and is not yet finished atthe moment of collision, i.e. at the moment at which the collisionobject is just touching the vehicle. However, it is advantageous if theacceleration of the vehicle seat cushion in the direction of the centerof the vehicle has already finished at the moment of collision. Thetransverse displacement of the occupant before the moment of collisionenables him not only to be displaced out of the danger zone, but also toundergo an acceleration which is in the same direction as theacceleration which the vehicle undergoes because of the collision. If,during the duration of the substantial transfer of momentum from thecollision object to the vehicle, the occupant is in a nonrigidconnection with the vehicle, i.e., for example, is in a transversemovement which can be guided by a seat cushion, then some of theacceleration which the vehicle experiences because of the collision willno longer be transferred to the occupant who has already beenaccelerated beforehand. This reduces the acceleration peaks which arehazardous for an occupant. This method is particularly advantageous ifthe strength of the acceleration of the occupant and the moment at whichthe acceleration begins and at which the acceleration ends, and thedisplacement distance are adapted by means of parameters relevant to theaccident, for example the accident severity, collision speed, occupant'sweight and occupant's height. An adaptation of the transversedisplacement of an occupant to an accident situation can take placesubstantially more easily and effectively by means of the displacementof one or more seat cushions than is possible by means of a displacementof the entire vehicle seat.

The moment which is situated by the triggering time t0 before the momentof collision turns out to be an advantageous moment for the triggeringof the transverse displacement of a seat cushion. In this case, thetriggering time t0 is specified as t₀=t₁+((−v_(k)(vk²+2 a_(km)s_(k1))0.5) a_(km)−1)+t₃. The variables occurring in this equation fordetermining the triggering time t0 are: t₁ is equal to the sum of thedelay times of the entire system for the transverse displacement of theseat, t₃ is the displacement time, i.e. the time during which the seatcushion moves toward the center of the vehicle, v_(k) is the speed atwhich the collision object moves in the direction of the vehicle seat atthe moment of collision, a_(km) is an average deceleration of thecollision object during the course of the collision, and s_(k1) is thedistance which the collision object covers during the course of thecollision from the vehicle outer skin into the vehicle interior up tothe moment of maximum transfer of momentum to the occupant. Thetriggering time t₀ may also be expanded by a constant which, forexample, is specific to the vehicle. Depending on the quality, theup-to-date nature and the amount of parameters which are available, themoment of triggering t₀ can be adapted to an accident by the abovealgorithm being expanded in nonlinear fashion or being supplemented byfurther parameters, such as, for example, the mass of the collisionobject or the structural rigidity of the vehicle at the point of impact.It has been found that the optimum acceleration values for a seatcushion lie above 5 g, in order to move an occupant sufficiently rapidlyout of the danger zone, and, on the other hand, acceleration values over10 g do not effect an gain in the speed of transverse displacement ofthe occupant, which justifies the measures required for this. A distanceof between 80 mm and 120 mm is advantageous as the displacementdistance, that is as the maximum possible distance by which a seatcushion is moved in the direction of the center of the vehicle.Displacement distances significantly below 80 mm do not move an occupantsufficiently far from the danger zone, and displacement distances above120 mm cause an occupant to be subjected to too severe a load by meansof the transverse displacement. In addition, very great displacementdistances are frequently not possible simply for space reasons. Thedisplacement time, i.e. the duration in which the seat cushion is movingsideways, is preferably between 100 ms and 150 ms.

1. A vehicle seat which effects a relative movement of an occupantsitting on it away from a side of the vehicle which faces a lateralimpact toward a center of the vehicle during or immediately before thelateral impact, wherein at least one seat cushion can be displacedseparately in relation to other seat components.
 2. The vehicle seat asclaimed in claim 1, wherein the separately displaceable seat cushion isformed by a seat surface.
 3. The vehicle seat as claimed in claim 1,wherein the separately displaceable seat cushion is formed by a seatback.
 4. The vehicle seat as claimed in claim 1, wherein a lockingdevice is provided which, after a transverse displacement has takenplace, secures the transversely displaced seat cushion in an endposition.
 5. A method for controlling a vehicle seat comprising the stepof: providing a seat in a vehicle which effects a relative movement ofan occupant sitting on the seat away from a side of the vehicle whichfaces a lateral impact toward a center of the vehicle during orimmediately before the lateral impact, wherein at least one seat cushioncan be displaced separately in relation to other seat components, andwherein the transverse displacement of the seat cushion begins beforethe moment of collision.
 6. The method as claimed in claim 5, whereinthe transverse displacement of the seat cushion is still continuing atthe moment of collision.
 7. The method as claimed in claim 6, wherein anacceleration of the seat cushion toward the center of the vehicle hasalready finished at the moment of collision.
 8. The method as claimed inclaim 5, wherein the transverse displacement of the seat cushion istriggered by triggering time to before the moment of collision, thetriggering time being t₀=t₁+((−v_(k) (v_(k) ²+2 a_(km) s_(k1))^(0.5))a_(km) ⁻¹)+t₃, and t₁ being the sum of the delay times of the transversedisplacement of the seat cushion, and t₃ being the displacement timeover which the displacement of a seat cushion lasts, and v_(k) being thespeed of a collision object at the moment of collision, and a_(km) beingan average deceleration of the collision object during the course of thecollision, and s_(k1) being the distance which the collision objectcovers during the course of the collision from the outer skin of thevehicle into the vehicle interior up to the moment of maximum transferof momentum to the occupant.
 9. The method as claimed in claim 8,wherein the displacement time t₃ is between 100 ms and 150 ms.
 10. Themethod as claimed in claim 8, wherein the displacement distance isbetween 80 mm and 120 mm.
 11. The method as claimed in claim 9, whereinthe displacement distance is between 80 mm and 120 mm.